How Do Scientists Distinguish Between Red Shift and a Red Dwarf's Natural Color?

[Ibby143]

How do scientists know if something is traveling away from us at any given moment, yes, it might be red, but it could be just a red dwarf star? How do they know it is the Doppler Effect in action, not just its natural colour?

 

[Jimmy]

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/redshf.html

The light from distant stars and more distant galaxies is not featureless, but has distinct spectral features characteristic of the atoms in the gases around the stars. When these spectra are examined, they are found to be shifted toward the red end of the spectrum.

Another page about Doppler Shift:
http://www.astro.ucla.edu/~wright/doppler.htm

 

[Nugatory]

How do scientists know if something is traveling away from us at any given moment, yes, it might be red, but it could be just a red dwarf star? How do they know it is the Doppler Effect in action, not just its natural colour?

We look at the individual spectral lines. For every element, there are a few frequencies at which it naturally absorbs and radiates energy, and these show up as lines in the spectrum. These lines form recognizable patterns, so if we see one of these patterns displaced towards the red or blue end of the spectrum we know that we're seeing Doppler at work.